Protein power: can 40 grams beat muscle shrinkage?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Men and women aged 18-39 years (17-39 years if military personnel) * Body mass index (BMI) between 18.5-32 kg/m2 * Routinely participate in aerobic and/or resistance exercise at least 2 days per week. * Willing to refrain from alcohol, smoking, smokeless nicotine products (includes e-cigarettes, vaping, chewing tobacco), and dietary supplements (i.e., vitamin D, probiotics) 24 hours before and during immobilization and final testing day. * Willing to only consume caffeine products provided by study staff during the study. * Supervisor approval for federal civilian employees and non-SRV active-duty military personnel stationed at NSSC. * Biological females must have normal menstrual cycles between 26-32 days in duration; 5 menstrual cycles within the past 6 months; or on continuous hormonal contraception (i.e., IUD or oral contraceptives without placebo). Exclusion Criteria: * Musculoskeletal injuries that may interfere with the safe use of crutches. * Personal or family history of thrombosis, or prior diagnosis of deep vein thrombosis (DVT) or pulmonary embolism (PE). * Metabolic or cardiovascular abnormalities, gastrointestinal disorders, neuromuscular disorders, lower-limb amputation, or muscle/bone wasting disorders (e.g., diabetes, cardiovascular disease, Crohn's disease, etc.). * Taking medication that affects macronutrient utilization (i.e., statins, corticosteroids, weight loss medications such as Ozempic, etc.). * Significantly abnormal blood clotting as determined by USARIEM Office of Medical Oversight (OMSO) or home duty station medical support (HMS). * Allergy to lidocaine (or similar local anesthetic). * Present condition of alcoholism, anabolic steroid use, or other substance abuse issues as determined by OMSO or HMS. * Blood donation within 8-wk of beginning the study. * Pregnant, trying to become pregnant, and/or breastfeeding (results of urine pregnancy test and self-report for breastfeeding will be obtained before body composition testing). * Unwilling or unable to consume study diets or foods provided due to personal preference and/or food allergies. * Unwilling or unable to adhere to study physical restrictions (i.e., no structured physical activity or recreational activity beyond activities of daily living) 24 hours before and during immobilization, and the final testing day. * Unwilling or unable to keep the knee brace on and walk with crutches during the immobilization phase.